Fall 2024 seminar, meeting Tuesday afternoons at 12:30pm.
In November, we have several sessions with Carlo Rovelli, based on this material: Princeton seminars. Leading up to November, we will focus primarily on topics that prepare us for the sessions with Rovelli — which will be a lot of ground to cover, since his lectures draw on many branches of physics including relativity theory, quantum mechanics, and statistical mechanics.
You’re encouraged to read Rovelli’s notes in advance and form your own opinion about what kind of philosophical view he takes. He is somewhat difficult to place in the landscape of recent philosophy! He’s an avowed naturalist, but resists simplistic reductions, e.g. of value to fact. He’s a scientific realist, but doesn’t think that physics describes “what exists and how it moves”. This is an interesting combination of views, and places Rovelli in relief against some of the main figures in recent philosophy. It also places Rovelli in an interesting line of natural philosophers including Aristotle, Descartes, Leibniz, Newton, and Einstein.
Here are some of the main topics that we plan to cover:
Substantivalism is the view that space (or spacetime) exists independently of the matter it contains. At least that’s the view to the first approximation. There are many ways in which that definition is not satisfactory, and it needs to be refined. For one of the most recent statements of the problem of formulation (and a proposal for how to fix it), see [@north2021physics]. HH: in my opinion, the real question is whether the current formulation of our spacetime theories (viz. GTR) is satisfactory, or whether we can do better, e.g. by not having a spacetime manifold anywhere in sight. This is related to the way that Hartry Field formulates the substantivalist-relationalist debate, see [@field1984can].
Relationalism is basically the negation of substantivalism, but more specifically, the belief that space (or spacetime) is nothing “over and above” relations between material objects.
Rovelli is an outspoken relationalist about spacetime.
For historical background, we need to look at the arc from Descartes to Newton, culminating in the Leibniz-Clarke correspondence, and then in Kant’s chirality argument. (But beware, the latter changes the nature of the debate from purely metaphysical to epistemological/semantic!) Fortunately for us, we have some of the top people in the world on these topics in our department: Dan Garber on Descartes and Leibniz and Des Hogan on Kant.
The next question is whether the discovery of the general theory of relativity (1915) changes the debate about substantivalism and relationalism. Our main source here is:
We will use the “hole argument” to focus our discussions.
The discussion of the hole argument raises questions about the meaning of determinism, which is itself a rather large subject. See e.g. Earman, Primer of Determinism.
Many philosophers have the impression that relativity theory — with its erasure of the distinction between space and time — tips the balance in favor of eternalism. Interestingly, Rovelli disagrees — although he does think that relativity theory rules out presentism.
Rovelli thinks that the lessons learned from spacetime physics (in favor of relationalism) can be generalized to quantum physics, and that it solves the interpretive problems (viz. the measurement problem).
There’s a piece of mathematics that really helps to understand the relational interpretation: the biorthogonal decomposition theorem. For more, see SEP: modal interpretation
Aside: Rovelli appears to be strongly antirealist about the quantum state. (See his paper on Heisenberg mechanics is the good mechanics.) But his view may be more subtle than it initially appears.
Statistical mechanics (developed late 19th century) has the amazing feature that it can derive a description of changes of macroscopic objects by applying probabilistic considerations to a large collection of microscopic objects. As such, it has looked to many like a success story of reduction to the microphysical. For any overview, see:
In recent years, philosophers of physics have displayed some worries about this reduction. Most of them want the reduction to work — and believe that it can — but there is a prima facie problem: the fundamental theory is time-reversal invariant, whereas the emergent theory is not.
Recall that Bertrand Russell claimed that “causality” is not needed in fundamental physics. Rovelli seems to agree — but he thinks that causality emerges at a higher level, and is an anthropocentric concept.
For the mathematics of relativity theory, our main sources are:
If you’re looking for more books or articles on any one of these topics, there are curated topical indexes at PhilPapers.org. For example: